vue2/src/core/components/keep-alive.ts

import { isRegExp, remove } from 'shared/util'
import { getFirstComponentChild } from 'core/vdom/helpers/index'
import VNode from 'core/vdom/vnode'
import type { VNodeComponentOptions } from 'typescript/vnode'

type VNodeCache = { [key: string]: VNode | null }

function getComponentName(opts?: VNodeComponentOptions): string | null {
  return opts && (opts.Ctor.options.name || opts.tag)
}

function matches(
  pattern: string | RegExp | Array<string>,
  name: string
): boolean {
  if (Array.isArray(pattern)) {
    return pattern.indexOf(name) > -1
  } else if (typeof pattern === 'string') {
    return pattern.split(',').indexOf(name) > -1
  } else if (isRegExp(pattern)) {
    return pattern.test(name)
  }
  /* istanbul ignore next */
  return false
}

function pruneCache(keepAliveInstance: any, filter: Function) {
  const { cache, keys, _vnode } = keepAliveInstance
  for (const key in cache) {
    const cachedNode: VNode | null = cache[key]
    if (cachedNode) {
      const name = getComponentName(cachedNode.componentOptions)
      if (name && !filter(name)) {
        pruneCacheEntry(cache, key, keys, _vnode)
      }
    }
  }
}

function pruneCacheEntry(
  cache: VNodeCache,
  key: string,
  keys: Array<string>,
  current?: VNode
) {
  const cached = cache[key]
  if (cached && (!current || cached.tag !== current.tag)) {
    //@ts-expect-error has void type
    cached.componentInstance.$destroy()
  }
  cache[key] = null
  remove(keys, key)
}

const patternTypes: Array<Function> = [String, RegExp, Array]

// TODO use defineComponent
export default {
  name: 'keep-alive',
  abstract: true,

  props: {
    include: patternTypes,
    exclude: patternTypes,
    max: [String, Number],
  },

  created() {
    this.cache = Object.create(null)
    this.keys = []
  },

  destroyed() {
    for (const key in this.cache) {
      pruneCacheEntry(this.cache, key, this.keys)
    }
  },

  mounted() {
    this.$watch('include', (val) => {
      pruneCache(this, (name) => matches(val, name))
    })
    this.$watch('exclude', (val) => {
      pruneCache(this, (name) => !matches(val, name))
    })
  },

  render() {
    const slot = this.$slots.default
    const vnode = getFirstComponentChild(slot)
    const componentOptions =
      vnode && vnode.componentOptions
    if (componentOptions) {
      // check pattern
      const name = getComponentName(componentOptions)
      const { include, exclude } = this
      if (
        // not included
        (include && (!name || !matches(include, name))) ||
        // excluded
        (exclude && name && matches(exclude, name))
      ) {
        return vnode
      }

      const { cache, keys } = this
      const key =
        vnode!.key == null
          ? // same constructor may get registered as different local components
            // so cid alone is not enough (#3269)
            componentOptions.Ctor.cid +
            (componentOptions.tag ? `::${componentOptions.tag}` : '')
          : vnode!.key
      if (cache[key]) {
        vnode!.componentInstance = cache[key].componentInstance
        // make current key freshest
        remove(keys, key)
        keys.push(key)
      } else {
        cache[key] = vnode
        keys.push(key)
        // prune oldest entry
        if (this.max && keys.length > parseInt(this.max)) {
          pruneCacheEntry(cache, keys[0], keys, this._vnode)
        }
      }

      vnode!.data!.keepAlive = true
    }
    return vnode || (slot && slot[0])
  },
}